CN207263931U - One kind is used for the constant temperature spectrum stabilization system of NaI (Tl) gamma energy spectrometer - Google Patents

Abstract

The utility model belongs to the measurement of radioactive instrument NaI (Tl) gamma energy spectrometer and application field, and in particular to one kind is used for the constant temperature spectrum stabilization system of NaI (Tl) gamma energy spectrometer；The purpose of this utility model; the purpose of this utility model seeks to solve the problems, such as the spectrum drift that can be produced by variation of ambient temperature during the measurement of NaI (Tl) gamma energy spectrometers relative method, and the semiconductor refrigerating unit includes hot-side heat dissipation fan (01), hot-side heat dissipation device (02), semiconductor chilling plate (03), heat-insulated patch (04), cool guiding block (05), temperature protection switch (06), cold end radiator (07) and cold end radiator fan (08)；The temperature protection switch (06) is installed on cool guiding block (05); cold end radiator (07) is installed on cool guiding block (05) upper surface; cold end radiator fan (08) is installed on above cold end radiator (07); heat-conducting silicone grease is uniformly smeared on the two sides of the semiconductor chilling plate (03), its cold end is placed with cool guiding block (05) lower end aligned.

Description

A constant temperature and stable spectrum system for NaI(Tl)γ energy spectrometer

technical field

The utility model belongs to the field of radioactive instrument NaI(Tl)γ energy spectrometer measurement and application, in particular to a constant temperature and stable spectrum system for NaI(Tl)γ energy spectrometer.

Background technique

The measurement of NaI(Tl) gamma energy spectrometer is generally a relative method, that is, the final measurement result is obtained by comparing and analyzing the standard spectrum established by the measured sample spectrum and the standard source. This requires that the physical conditions of the sample measurement are highly consistent with the conditions of the library construction using the standard source, so that the measurement results can be accurate. In practical applications, it is found that the temperature in the environmental conditions will seriously affect the accuracy of the NaI(Tl)γ spectrometer. When the temperature fluctuates or is different from the temperature when the library was built, it will cause the peak position of the instrument spectrum to drift. As the temperature decreases, the γ spectrum distribution will drift to the right; as the temperature increases, the γ spectrum distribution will drift to the left; moreover, this drift is not a linear drift, and the drift situation at the low-energy end and high-energy end is not completely consistent.

There have been a lot of researches on the problem of spectral drift caused by temperature in the measurement of NaI(Tl) γ-ray spectrometer. If peak position drift occurs, the gain of the amplifier can be changed by feedback of the characteristic peak position drift detection, or according to the peak position drift. Detection to adjust the high voltage, or use standard sources such as 241Am, 137Cs or use LED light sources to generate relatively pure peaks as reference characteristic peaks for peak position drift monitoring. In addition, there is also digital stabilization at present, which uses reference sources such as 137Cs to measure its characteristic peak position for energy calibration to obtain the initial energy calibration curve, and then in practical applications, according to the energy calibration curves calibrated at different times to real-time scale and correct the stability. Spectrum, the key to this method is the accuracy of peak finding and real-time scale.

For the spectrum stabilization method, a lot of work has been done in China, and there are corresponding researches on methods such as the use of reference sources, LED light sources, and digital spectrum stabilization. In 2009, Ao Qi, Department of Engineering Physics, Tsinghua University, and others performed digital stabilization work on NaI(Tl) spectrometer based on reference source characteristic peaks. In the temperature range (20-50) °C, the source peaks of 241Am and 60Co In the qualitative detection experiment, it is shown that the stable spectrum performance in the high and low energy ranges is reliable. But at the same time, it is also objectively pointed out that this method, like other stabilization methods, is not suitable for sudden temperature changes, and it is necessary to stop the measurement and re-scale. Because the smaller the real-time scale time t used in real-time spectrum stabilization, the greater the allowable temperature change rate, and the worse the accuracy of spectrum stabilization using reference sources in this case.

Combined with the spectrum stabilization methods proposed at home and abroad for the problem of spectral drift caused by environmental temperature changes, they can be roughly divided into two categories: one is to use reference sources (137Cs, LED light sources, etc.), according to the spectral drift caused by temperature changes in the measurement, real-time Adjust the working voltage of the detector, the amplification factor of the back-end electronics, etc. to achieve stable spectrum, that is, reference source stable spectrum; the other is to use the reference source to perform real-time energy calibration according to temperature changes to achieve stable spectrum, that is, digital stable spectrum .

Existing problems:

1) Neither the reference source nor the digital spectrum stabilization can solve the impact of temperature changes on the luminous efficiency of the detector crystal, the luminous decay time, and the gain of the photomultiplier tube.

2) For the reference source stabilization spectrum, since the temperature drift is nonlinear, it cannot be applied when the characteristic peak and the peak to be measured deviate far away when the temperature difference is large. In addition, the use of reference sources increases the background of the instrument, which brings inconvenience to the transportation, installation and use of the instrument.

3) For the digital stabilization spectrum, it cannot be applied in the case of sudden temperature changes, and the digital stabilization spectrum is greatly disturbed by the background spectrum (reference source).

In summary, the current NaI(Tl)γ spectrometer based on the relative method has an absolute dependence on the ambient temperature, and the use of reference sources, digitization and other spectral stabilization methods are all compensation methods, which cannot fundamentally solve the problem of temperature’s impact on the energy of scintillation crystals. Resolution, scintillation decay time and scintillation photon number, and the influence of index parameters such as the dark current of the photomultiplier tube. At present, a large number of laboratories completely solve the influence of ambient temperature by installing air conditioners to adjust the room temperature, but this is very inconvenient in actual operation.

The following problems exist in the use of air conditioners to adjust the constant temperature:

1) For a laboratory with a large room, it takes a certain amount of time to reach the required temperature, and there is a certain degree of difficulty in maintaining the temperature in a large indoor space;

2) For the constant temperature method of using air conditioners to adjust the room temperature, there are certain limitations in the case where the NaI(Tl)γ spectrometer and other instruments are not at the same working temperature;

3) The air conditioner is used to adjust the room temperature to keep the temperature constant, and the low-background lead shielding room and outdoor temperature of the NaI(Tl)γ spectrometer cannot be balanced in a short time, which will still have a certain impact on the measurement.

Contents of the invention

Purpose of the present invention, the purpose of this utility model will solve the spectral drift problem that can produce when the relative method of NaI(Tl) gamma energy spectrometer is measured by ambient temperature change, propose to adopt semiconductor refrigeration, PID constant temperature control to be used for NaI(Tl) Tl) constant temperature and stable spectrum system of energy spectrometer. The library building, calibration and measurement of the instrument can be completed at the same temperature, which solves the current situation that the instrument must depend on the ambient temperature of the laboratory, and fundamentally solves the problem of the influence of the ambient temperature on the energy spectrum measurement.

Technical scheme of the present invention is:

A constant temperature and stable spectrum system for NaI(Tl) gamma energy spectrometer, comprising an intelligent semiconductor refrigeration unit, an intelligent PID constant temperature control and a thermal insulation shell.

The semiconductor refrigeration unit includes a hot end cooling fan, a hot end radiator, a semiconductor cooling sheet, a thermal insulation sticker, a cold guide block, a temperature protection switch, a cold end radiator, and a cold end cooling fan; the temperature protection switch is installed on the guide On the cold block, the cold end radiator is installed on the upper surface of the cooling block, the cold end cooling fan is installed above the cold end radiator, the two sides of the semiconductor cooling sheet are evenly coated with thermal conductive silicon grease, and the cold end is aligned with the lower end of the cold conduction block placed, the lower end of the semiconductor refrigeration sheet is provided with a hot end radiator, and the lower end of the hot end radiator is provided with a hot end cooling fan.

The intelligent PID constant temperature control includes a temperature detection sensor, a wireless transmission circuit and a control program.

The heat preservation shell includes a bottom cover, a polystyrene insulation layer and a polytetrafluoroethylene shell; wherein the bottom cover is arranged at the lower end of the cold guide block, and is connected with the cold guide block by screws, and the fixing device is arranged at the upper end of the bottom cover , the detector is fixed on the upper end of the fixing device; the polytetrafluoroethylene shell is set outside the intelligent semiconductor refrigeration unit, and the polystyrene insulation layer is arranged on the inner layer of the polytetrafluoroethylene shell.

The beneficial effects of the present invention are:

The utility model relates to a constant temperature and stable spectrum system for NaI(Tl) gamma energy spectrometer, which adopts intelligent PID constant temperature control, 0-40°C arbitrary temperature setting, and 0.1°C precision constant temperature maintenance;

The utility model relates to a constant temperature and stable spectrum system for NaI(Tl) gamma energy spectrometer. The semiconductor refrigeration component can be used for heating at the hot end and cooling at the cold end, and can realize constant temperature at any temperature from 0 to 40°C. Use requirements at 20°C;

The utility model relates to a constant temperature and stable spectrum system for NaI(Tl) gamma energy spectrometer, which adopts wireless temperature transmission mode to monitor the real-time temperature of the whole system, and can perform remote monitoring operation;

The utility model relates to a high-precision 50°C temperature switch used in a constant temperature and stable spectrum system for NaI(Tl) gamma energy spectrometer, which prevents the temperature of the semiconductor hot end from being too high and the system circuit short circuit, etc., and improves the use of the whole system safety;

The utility model relates to a constant temperature and stable spectrum system for NaI (Tl) gamma energy spectrometer, which can fully realize the constant temperature effect of NaI (Tl) detectors, and fundamentally solves the problem of temperature for NaI (Tl) gamma energy spectrum The problem of spectral drift caused by the instrument. Relative to reference source stabilization, digital stabilization and other methods fundamentally solve the problem of the influence of temperature on scintillation crystals, photomultiplier tubes, etc., and are suitable for the application of full-spectrum measurement and analysis.

The utility model has low power consumption (about 25W), can be used continuously for a long time, avoids the absolute dependence of the NaI(Tl)γ energy spectrometer on the laboratory environment temperature, and the high-precision constant temperature system also improves the measurement accuracy of the instrument.

Description of drawings

Fig. 1 is a kind of semiconductor installation fixed schematic diagram that is used for NaI(Tl) gamma energy spectrometer constant temperature and stable spectrum system of the utility model;

Fig. 2 is a schematic diagram of a semiconductor refrigeration unit for a constant temperature and stable spectrum system of a NaI(Tl) gamma energy spectrometer in a utility model;

Fig. 3 is a kind of overall schematic diagram that is used for NaI (Tl) gamma energy spectrometer constant temperature and stable spectrum system of utility model;

Fig. 4 is a kind of overall work schematic diagram that is used for NaI(Tl) gamma energy spectrometer constant temperature and stable spectrum system of the utility model;

Detailed ways

Below in conjunction with accompanying drawing and embodiment the present invention is further introduced:

A constant temperature and stable spectrum system for NaI(Tl) gamma energy spectrometer, comprising an intelligent semiconductor refrigeration unit, an intelligent PID constant temperature control and a thermal insulation shell.

The semiconductor refrigeration unit includes a hot end cooling fan 1, a hot end radiator 2, a semiconductor cooling sheet 3, a thermal insulation sticker 4, a cold guide block 5, a temperature protection switch 6, a cold end radiator 7 and a cold end cooling fan 8; The temperature protection switch 6 is installed on the cooling block 5, the cold end radiator 7 is installed on the upper surface of the cooling block 5, the cold end cooling fan 8 is installed on the top of the cold end radiator 7, and the two sides of the semiconductor cooling sheet 3 are uniform Apply heat-conducting silicone grease, and its cold end is aligned with the lower end of the cold-conducting block 5. The lower end of the semiconductor cooling sheet 3 is provided with a hot-end radiator 2, and the lower end of the hot-end radiator 2 is provided with a hot-end cooling fan 1.

The intelligent PID constant temperature control includes a temperature detection sensor, a wireless transmission circuit and a control program.

Described thermal insulation shell comprises bottom cover 13, polystyrene insulation layer 11 and polytetrafluoroethylene shell 12; Wherein said bottom cover 13 is located at the lower end of cold conduction block 5, is connected with cold conduction block 5 by screw, and described fixing The device 9 is set on the upper end of the bottom cover 13, and the detector 15 is fixed on the upper end of the fixing device 9; the polytetrafluoroethylene shell 12 is set outside the intelligent semiconductor refrigeration unit, and the polystyrene insulation layer 11 is set on the polytetrafluoroethylene shell 12 inner layers.

The utility model relates to a constant temperature and stable spectrum system for NaI(Tl) gamma energy spectrometer. The technical solution in the utility model will be described completely and clearly below in conjunction with the accompanying drawings.

The utility model relates to a constant temperature and stable spectrum system for NaI(Tl) gamma energy spectrometer, which is composed of an intelligent semiconductor refrigeration unit, an intelligent PID constant temperature control and a heat preservation shell. As shown in Figure 2, the semiconductor refrigeration unit includes a hot-end cooling fan 01, a hot-end radiator 02, a semiconductor cooling sheet 03, a thermal insulation sticker 04, a cold-conducting block 05, a temperature protection switch 06, a cold-end radiator 07, and a cold-end radiator. Cooling fan 08; intelligent PID constant temperature control includes temperature detection sensor, wireless transmission circuit and control program; thermal insulation shell includes polystyrene (EPS) thermal insulation layer 11, polytetrafluoroethylene (PTFE) shell 12, semiconductor refrigeration unit fixed installation bottom Cover 13 and fixing screw hole 14 are formed.

The utility model relates to a constant temperature and stable spectrum system for NaI(Tl) gamma energy spectrometer. The specific implementation method is as follows: a semiconductor refrigeration sheet 3, a heat insulation sticker 4, a cold guide block 5, and a temperature protection switch 6 are shown in Figure 1 Install the temperature protection switch on the cooling block 5 first, connect the terminal of the temperature protection switch to the system power supply ground wire end in series, and then evenly apply heat-conducting silicone grease on both sides of the semiconductor refrigeration sheet 3, and place the cold end in alignment with the cooling block. The hot end faces the opening direction of the heat insulation sticker on the bottom cover 13, and then paste the heat insulation sticker around the semiconductor, and then install the radiator 7 on the cold end and the radiator 2 on the hot end, fix them with long studs, and then install the fans respectively 1 and 8, install the insulation layer 11 on the shell 12 first, and then install the temperature sensor, signal communication line and power supply line, the temperature sensor signal is transmitted to the intelligent PID controller through wireless transmission, and the power supply line of the semiconductor refrigeration chip is connected to the receiving PID controller Regulated solid state relay output.

The utility model relates to a NaI(Tl) gamma energy spectrometer constant temperature stabilization system starting, as shown in Figure 4, firstly monitors in real time whether the temperature protection switch is triggered, if the temperature is too high, the hardware will directly cut off the power to mediate the system, Otherwise, allow to set the target temperature value in the intelligent PID controller, and then start the constant temperature system. When the system is started, it will automatically enter the PID parameter setting and storage program. At this time, the system monitors the temperature inside the constant temperature system in real time and transmits it to the PID controller in a wireless way. After the PID parameter setting is completed, it enters the automatic constant temperature stage. The target temperature value is automatically adjusted to heating or cooling to meet the requirements of the constant temperature of the system.

The utility model relates to a constant temperature and stable spectrum system for NaI(Tl) gamma energy spectrometer with simple structure and high control precision of 0.1°C, which fully meets the needs of NaI(Tl) gamma energy spectrometer for measurement and application at room temperature, and solves the problem of The dependence of NaI(Tl)γ energy spectrometer on ambient temperature and the spectral drift caused by the influence of temperature have been solved for a long time.

Claims (2)

1. A constant temperature and stable spectrum system for NaI (Tl) gamma energy spectrometer, characterized in that: comprise intelligent semiconductor refrigeration unit, intelligent PID constant temperature control and heat preservation shell; The semiconductor refrigeration unit includes a hot-end cooling fan (01), a hot-end radiator (02), a semiconductor cooling sheet (03), a thermal insulation sticker (04), a cold-conducting block (05), a temperature protection switch (06), The cold end radiator (07) and the cold end cooling fan (08); the temperature protection switch (06) is installed on the cooling block (05), and the cold end radiator (07) is installed on the cooling block (05) On the surface, the cooling fan (08) at the cold end is installed above the radiator (07) at the cold end, and the two sides of the semiconductor cooling sheet (03) are evenly coated with heat-conducting silicone grease, and the cold end is aligned with the lower end of the cold-conducting block (05). , the lower end of the semiconductor cooling plate (03) is provided with a hot end radiator (02), and the lower end of the hot end radiator (02) is provided with a hot end cooling fan (01). 2. a kind of constant temperature and stable spectrum system for NaI(Tl) gamma energy spectrometer as claimed in claim 1, is characterized in that: described heat preservation shell comprises bottom cover (13), polystyrene insulation layer (11) and a polytetrafluoroethylene shell (12); wherein the bottom cover (13) is located at the lower end of the cold guide block (05), and is connected with the cold guide block (05) by screws, and the fixing device (09) is located at the bottom cover ( 13) The upper end, the detector (15) is fixed on the upper end of the fixing device (09); the polytetrafluoroethylene shell (12) is set outside the intelligent semiconductor refrigeration unit, and the polystyrene insulation layer (11) is set on the polytetrafluoroethylene Vinyl fluoride shell (12) inner layer.